1. Field of the Invention
The present invention relates to a crystalline mixture solid composition which comprises xcex1-D-glucopyranosyl-1,1-mannitol and xcex1-D-glucopyranosyl-1,6-sorbitol and/or a small amount of xcex1-D-glucopyranosyl-1,1-sorbitol and to a production process therefor.
2. Prior Art
Hydrogenated isomaltulose (hydrogenated palatinose) has been known as one of low-calorie sweeteners which do not cause a carious tooth. The hydrogenated isomaltulose is a mixture of two sugar alcohols, that is, an almost equimolar mixture of xcex1-D-glucopyranosyl-1,1-mannitol (to be abbreviated as GPM hereinafter) and its isomer xcex1-D-glucopyranosyl-1,6-sorbitol (to be abbreviated as GPS-6 hereinafter), which can be obtained by forming isomaltulose (palatinose) from cane sugar by means of a transferase and then hydrogenating the palatinose.
The hydrogenated isomaltulose is known as an extremely useful sweetener which exhibits an excellent sweet taste like cane sugar, has low hygroscopicity, heat resistance, acid resistance, alkali resistance, excellent processability such as tablettability and granulability, and physiological properties such as low calorie, noncariogenic properties and insulin non-irritating properties.
As the method of crystallizing the hydrogenated isomaltulose, H. Schiweck""s report (Alimenta. 19,5-16,1980) discloses a vacuum crystalizar process. However, this process is very complicated and repeats the steps of evaporation, aging and centrifugation, thereby consuming a huge amount of energy and boosting product costs.
JP-A 60-181094 (the term xe2x80x9cJP-Axe2x80x9d as used herein means an xe2x80x9cunexamined published Japanese patent applicationxe2x80x9d) discloses a process for crystallizing an aqueous solution of hydrogenated isomaltulose having a solid content of about 80% in a vacuum crystallization apparatus. However, since this process requires a special apparatus such as a vacuum crystallization apparatus and employs a batch system, it is not practical due to its low production efficiency.
JP-A 62-148496 discloses a process for crystallizing hydrogenated isomaltulose in accordance with a kneading method using seed crystals. This process is used to crystallize mainly a GPM component out of hydrogenated isomaltulose components. That is, the water content of the hydrogenated isomaltulose is adjusted to a range of more than 5% and 20% or less, the liquid temperature is maintained at a range of 50 to 90xc2x0 C. according to the content of water, seed crystals are added and mixed, and the mixed product is solidified by cooling the temperature at around room temperature, dried and ground to obtain crystallized hydrogenated palatinose powders. However, this process has a problem with processing (such as grindability) as the kneaded product obtained by this process has high stickiness and also a problem with distribution (such as caking and the propagation of microorganisms) as cooling and drying take long time.
It is also known that when a transferase is caused to act on cane sugar, trehalulose (xcex1-D-glucopyranosyl-1,1-fructose) is formed in addition to isomaltulose. Generally speaking, when hydrogenated isomaltulose is produced, after only isomaltulose is obtained by crystallization separation, the residual mixture containing trehalulose is discarded or disposed at a low cost. It is known that trehalulose is converted into GPM and xcex1-D-glucopyranosyl-1,1-sorbitol (to be abbreviated as GPS-1) by hydrogenation. That is, when a transferase is caused to act on cane sugar as a raw material and the obtained mixture is hydrogenated, a mixture of GPM, GPS-6 and GPS-1 can be obtained. To obtain such a mixture, a process is known as disclosed in JP-A 7-51079. This process comprises the first step of carrying out the conversion reaction of cane sugar, the second step of removing unreacted cane sugar and the third step of carrying out a hydrogenation reaction in the presence of a catalyst. As for solidification, the above publication discloses a fine particulate product obtained by vaporizing water for solidification and grinding. However, the product is an amorphous and glass-like solid, has high hygroscopicity, and is difficult to handle and easily worn by abrasion during circulation. Generally speaking, when the content of a honey portion (GPS-1 and the residual sugars in the present invention) in a crystalline mixture solid is high, the product has high moisture absorption and is difficult to handle. Consequently, a crystalline mixture solid composition which has a low content of the honey portion and excellent handling ease and can be produced at a low cost has been desired.
It is an object of the present invention to provide a crystalline mixture solid composition which rarely has moisture absorption, is easy to handle and dissolve, and comprises GPM and GPS-6 and/or a small amount of GPS-1 in an extremely short period of time with small-scale equipment by a process which can save power and does not take much time and labor.
It is another object of the present invention to provide an industrially advantageous process for producing the above crystalline mixture solid composition of the present invention.
Other objects and advantages of the present invention will become apparent from the following description.
According to the present invention, firstly, the above objects and advantages of the present invention are attained by a crystalline mixture solid composition which comprises xcex1-D-glucopyranosyl-1,1-mannitol, xcex1-D-glucopyranosyl-1,6-sorbitol and 0.01 to 1.99 wt % of xcex1-D-glucopyranosyl-1,1-sorbitol (the above wt % is based on the total weight of the xcex1-D-glucopyranosyl-1,1-mannitol, xcex1-D-glucopyranosyl-1,6-sorbitol and xcex1-D-glucopyranosyl-1,1-sorbitol) (may be referred to as xe2x80x9cfirst crystalline mixture solid composition of the present inventionxe2x80x9d hereinafter).
According to the present invention, secondly, the above objects and advantages of the present invention are attained by a thin scale crystalline mixture solid composition which comprises xcex1-D-glucopyranosyl-1,1-mannitol and xcex1-D-glucopyranosyl-1,6-sorbitol (may be referred to as xe2x80x9csecond crystalline mixture solid composition of the present inventionxe2x80x9d hereinafter).
According to the present invention, thirdly, the above objects and advantages of the present invention are attained by a process for producing a crystalline mixture solid composition, comprising the steps of supplying a composition comprising 50 to 80 wt % of xcex1-D-glucopyranosyl-1,1-mannitol, 1 to 50 wt % of xcex1-D-glucopyranosyl-1,6-sorbitol and 0.01 to 20 wt % of xcex1-D-glucopyranosyl-1,1-sorbitol into a kneader to knead and cool it so as to produce a composition, mixing the composition with a hydrophilic solvent, separating solid matter from a liquid, and removing water and the solvent from the solid matter (the above wt % is based on the total weight of the xcex1-D-glucopyranosyl-1,1-mannitol, xcex1-D-glucopyranosyl-1,6-sorbitol and xcex1-D-glucopyranosyl-1,1-sorbitol) (may be referred to as xe2x80x9cfirst production process of the present inventionxe2x80x9d hereinafter).
According to the present invention, fourthly, the above objects and advantages of the present invention are attained by a process for producing a crystalline mixture solid composition, comprising the steps of mixing an aqueous solution containing 50 to 80 wt % of xcex1-D-glucopyranosyl-1,1-mannitol, 1 to 50 wt % of xcex1-D-glucopyranosyl-1,6-sorbitol and 0 to 20 wt % of xcex1-D-glucopyranosyl-1,1-sorbitol with a hydrophilic solvent, separating the formed precipitate from a liquid, and removing water and the solvent from the precipitate (the above wt % is based on the total weight of the xcex1-D-glucopyranosyl-1,1-mannitol, xcex1-D-glucopyranosyl-1,6-sorbitol and xcex1-D-glucopyranosyl-1,1-sorbitol) (may be referred to as xe2x80x9csecond production process of the present inventionxe2x80x9d hereinafter).